1. Field of the Invention
The present invention relates to a semiconductor device and in particular, to a ball grid array (BGA) type semiconductor device.
2. Description of the Related Art
Recently, the electronic apparatuses having a built-in semiconductor device are becoming thinner and smaller in size and it has become necessary to reduce the thickness and size of the semiconductor device to be built in those electronic apparatuses. To cope with this, a ball grid array (BGA) type semiconductor device is now beginning to be used in practice.
FIG. 6 is a cross sectional view of a conventional BGA semiconductor device mounted on a printed circuit board. As shown in FIG. 6, in the conventional BGA type semiconductor device, a semiconductor chip 11 is mounted on a wiring substrate 12 made from an organic resin or ceramic as a main material, and a bonding wire 13 connects a bonding pad (not depicted) of the semiconductor chip 11 to a conductive wiring (not depicted) formed on a surface of the wiring substrate 12 where the semiconductor chip 11 is mounted. A seal resin 14 covers the semiconductor chip 11 and the bonding wire 13 on the wiring substrate 12. Weld balls 16 as external terminals are arranged on a lattice shape on the land 15 as connection terminals connected to the aforementioned conductive wiring formed on the opposite surface of the wiring substrate 12 not having the semiconductor chip 11. It should be noted that the connection between the bonding pad (not depicted) of the semiconductor chip 11 and the conductive wiring (not depicted) formed on the wiring substrate 12 is not limited to the connection using the bonding wire 13. The connection may also be a flip chip connection using a bump electrode formed on the bonding pad (not depicted) of the semiconductor chip 11.
As can be seen from the cross sectional view of the BGA type semiconductor device mounted on the printed circuit board of FIG. 6, in the aforementioned conventional BGA type semiconductor device, the weld balls 16 serving as external terminals provided on the wiring substrate 12 of the BGA type semiconductor device thermally attached to the land (connection terminal) 22 formed on the mounting surface of the printed circuit board 21 by using the reflow method or the like. Here, a difference is present between the thermal expansion coefficients of the wiring substrate 12 of the BGA type semiconductor device and the printed circuit board 21. Accordingly, a stress is caused by the thermal expansion difference during heating and the thermal shrinking difference during cooling. The stress is concentrated in the weld balls 16 of the BGA type semiconductor device as junction portions and the weld balls 16 are cracked or broken. That is, a junction failure is caused.
It is therefore an object of the present invention to provide a BGA type ;semiconductor device capable of preventing a junction failure due to cracks and breakage of the weld balls of the BGA type semiconductor device when mounted on the printed circuit board, thus increasing the reliability of mounting on the printed circuit board.
The semiconductor device according to the present invention comprises: a wiring board having on its first surface a conductive wiring and on its second surface a connection terminal connected to the conductive wiring; a semiconductor chip mounted on the first surface of the wiring board and electrically connected to the conductive wiring; a sealing resin for sealing the semiconductor chip; and a conductive board having a pair of terminals arranged at a distance and on different surfaces of the conductive board, wherein one of the terminals provided on the conductive board is connected to the connection terminal formed on the wiring board and the other of the terminals provided on the conductive board serves as an external terminal.
Moreover, the device further comprises: an insulation tape on which a plurality of the conductive boards are arranged; and an insulation cover for the surface of the conductive board not facing the insulation tape, wherein the pair of terminals arranged on the conductive board protrude through the insulation tape or the insulation cover. The plurality of conductive boards arranged on the insulation tape are located to correspond to positions of the plurality of connection terminals formed on the wiring board.
Moreover, a slit is provided through the insulation tape and the conductive board around the terminals arranged on the conductive board.
Moreover, the device further comprises insulation covers covering both surfaces of the conductive board, wherein the pair of terminals arranged on the conductive board protrudes through the insulation covers. A plurality of the conductive boards are arranged to correspond to positions of a plurality of the connection terminals formed on the wiring board.
Moreover, the pair of terminals arranged on the conductive board are weld balls and the conductive board is connected to the wiring board by reflow.
According to this invention, one of the terminals arranged on the conductive board and connected to the connection terminal formed on the wiring board is arranged apart from the other of the terminals arranged on the conductive board to serve as an external terminal. Moreover, a slit is provided around the terminals provided on the conductive board.